Guanfacine is a central alpha2A-adrenergic receptor agonist indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) as monotherapy and as adjunctive therapy to stimulant medications. It is also indicated is indicated in the management of hypertension, either alone or in combination with other antihypertensive agents, especially thiazide-type diuretics. Guanfacine hydrochloride, a pharmaceutically acceptable salt of guanfacine, is a white to off-white crystalline powder, sparingly soluble in water (approximately 1 mg/mL) and alcohol and slightly soluble in acetone. The chemical designation for guanfacine hydrochloride is N-amidino-2-(2,6-dichlorophenyl)-acetamide monohydrochloride. The chemical structure is:

Guanfacine and its pharmaceutically acceptable salts is disclosed in U.S. Pat. No. 3,632,645. U.S. Pat. No. 5,854,290 discloses the method of treating a behavioral disinhibition (e.g. Attention-Deficit Hyperactivity Disorder) in a primate with minimal sedative side effects by administering thereto a therapeutically effective amount of guanfacine.
U.S. Pat. Nos. 6,287,599 and 6,811,794 describe sustained release tablet compositions of guanfacine, comprising at least one non-pH dependent sustained release agent; and at least one pH dependent agent that increases the rate of release of guanfacine from the tablet at a pH in excess of 5.5.
Guanfacine is presently marketed only in solid dosage forms i.e. immediate release and extended release tablets for oral administration. However, solid dosage forms are not suitable for some patients who have difficulty in swallowing solid dosage forms e.g. pediatric patients or incapacitated patients. Further, solid dosage forms may not be convenient, when chronic therapy is needed. Therefore, there exists a clear need in the art for oral liquid compositions of guanfacine. To date, no liquid compositions of guanfacine are known. The only FDA approved guanfacine products are solid dosage forms i.e. tablets. In view of this, liquid compositions of guanfacine are desirable over presently available solid dosage forms, as they would offer better patient compliance, convenience and flexible dosing regimen.
However, a prime concern with any liquid formulation is the stability of the active ingredient, both short term and over the time. Inventors of the present application have for the first time developed oral liquid compositions of guanfacine. The compositions are stable both during manufacturing and shelf life. Said liquid compositions are suitable for both immediate release and extended release of guanfacine.
Therefore, the present invention is a significant advance over the available solid dosage forms of guanfacine and fulfills the long felt need to improve patient compliance by providing an oral liquid composition of guanfacine with acceptable stability.
Oral liquid compositions of guanfacine also offer additional advantages as are easy to manufacture with functional reproducibility. The oral liquid compositions described herein are provided with a pleasant mouth feel thereby further enhancing patient compliance and ease of administration.